Oliver McFadden's Dante port
of the open-source id Tech 4 engine and Doom 3 code-base has been ported to Google's Android operating system for mobile devices.
While the open-source Doom 3 can now run on Android, it's not an easy build process at this point. In addition, the performance of Dante on Android is quite poor and will take time as the OpenGL ES support is optimized
in various ways, there needs to be improvements for handling Doom 3 with touchscreen input, and there isn't currently audio support within the id Tech 4 engine for Android.
Those interested in learning more about the open-source Doom 3 "Dante" on Android, see McFadden's blog post
In related news, it looks like a Blizzard may be heading towards Tux